The present invention relates to a device for handling a bone screw.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
A device of this type is known from EP 1 694 226 B1. This device serves for connecting a bone screw, which is anchored in a bone, in particular a vertebra, with a vertebral rod. For this purpose the bone screw has a forked head into which the vertebral rod is inserted and where it is fixed by means of a grub screw or by means of a cap nut. In order to join the forked head with the vertebral rod, a device is required with which the vertebral rod is inserted or slid between the two legs of the fork head. The device is constructed in the manner of pliers and has two jaws whose proximate ends face toward the user and whose distal ends engage on the head of the bone screw. The two jaws are articulately or pivotally interconnected via a transverse axis so that a pushing together of the proximal ends causes an opening of the distal ends so that the bone screw can be grasped.
In order to move the vertebral rod in the direction of the fork head of the bone screw, an adjustment tool is provided which is screwed between the two jaws. For this the adjustment tool has a section with an outer threading, which is screwed into an internal threading provided on the insides of the two jaws. A disadvantage is that the internal threading is configured as two threading halves, as a result of being provided on the two insides of the jaws. On one hand the manufacture of the internal threading is relative work intensive because after assembling the two jaws the threadings, in particular their transition from one jaw to the other jaw, has to be in perfect alignment, on the other hand the support of the jaws for pivoting relative to each other causes a relatively great play between the internal threading of the jaws and the outer threading of the adjustment tool.
It would therefore be desirable and advantageous to provide an improved device in which the adjustment tool is guided more precisely in the housing of the device.